Group theoretical treatment of the low-temperature phase transition of the Cd{sub 6}Ca 1/1-cubic approximant
- Department of Materials Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510 (Japan)
- Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)
- Ecotopia Science Institute, Nagoya University, Nagoya 464-8603 (Japan)
- Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581 (Japan)
An antiparallel orientational transition is reported for an intermetallic compound, i.e., Cd{sub 6}Ca crystal, which is a 1/1-1/1-1/1 crystalline approximant to the icosahedral quasicrystal Cd{sub 5.7}Ca. A group theoretical analysis based on the Landau theory predicts that the space group of the low-temperature phase is either C2/c or C2/m, in good agreement with the observations. Accordingly, two types of orientational orderings of Cd{sub 4} tetrahedra, which are located in the center of icosahedral clusters, may occur below 100 K: In both cases, the Cd{sub 4} tetrahedra are orientationally ordered in an antiparallel fashion along the [110] direction of the high temperature body-centered-cubic phase. Such a transition in a metal is reminiscent of orientational transitions in molecular solids.
- OSTI ID:
- 20719786
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 72, Issue 17; Other Information: DOI: 10.1103/PhysRevB.72.174211; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCC LATTICES
CADMIUM ALLOYS
CALCIUM ALLOYS
CRYSTALS
ELECTRON DIFFRACTION
INTERMETALLIC COMPOUNDS
METALS
MONOCLINIC LATTICES
ORDER-DISORDER TRANSFORMATIONS
ORIENTATION
SOLIDS
SPACE GROUPS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
X-RAY DIFFRACTION